Draft tube for hydraulic turbines or other fluid motors



Oct. 26 1926.

L. F. MOODY DR-AFT TUBE FOR HYDRAULIC TURBINES OR OTHER FLUID MOTORS '7 Sheets-Sheet: l

Filed yApril 14 Oct. 26 1926.

L. F. MOODY DRAFT TUBE FOR HYDRAULIC TURBINES OR OTHER FLUID MOTORS Filed April 14 Oat.` 26 1926.

L. F. MOODY DRAFT TUBE FOR HYDRAULIC TURBINES OR OTHER FLUID MOTORS L. F. MOODY DRAFT TUBE FOR HYDRAULIC TURBINES OR OTHER FLUID MOTORS 1916 '7 Sheets-Sheet 4 Filed April 14 nuewfo'c Oct. 26 1926.

L. F. MOODY DRAFT TUBE FOR HYDRAULIC TURBINES 0R OTHER FLUID MOTORS t zu. m 5 J o w n 5 w m, m@ Vw 5 .m f5 6 5 w m z. 4 .mf d m m Oct. 26 1926.

. L. F. MOODY DRAFT TUBE FOR HYDRAULIC TURBINES OR OTHER FLUID MOTORS Filed April 14, 1916 7 Sheets-Sheet` 6 i l y INVEIVTI? BY I ATOHIVEYJ.

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L. F. MOODY DRAFT TUBE FR HYDRAULIC TURBINES 0R OTHER FLUID MOTORS alon' the fo lowing lines: 1.

Passed oci. 26, 192e.

- UI-JIT11D:STATES LEWIS animi! Incom?,V 01? T361? i naa-rr 'runs ron rnnaunio 'iiuncsriiriisjci?.V 'organ pharmacies April 14. isis. serial il. einer?.

This invention relates to rotary fluid motors and has for its object to increase the eilicien'cy by discharging the fluid fromthe runner so as to utilize its velocity head to ini,

crease the .proportion of the total pressure head eilective upon the runner. i

The invention is applicableto uid motors in general, whether using liquid, air, gas, steam, or other va or, but is especially described herein wi reference to hydraulic turbines having runners-of great ower, and

high seciiic speed. Recent deve o ment ofv y ra the h ulic turbine has been in t e direction of increased sizes of units, with run'- ners of great power and high specific speed. Further pro calls for im rovements ncrease in slfieciic speed of runners without sacrifice o eicienc or increase of the'maximum.

D elliciency o runners of hih specific speed;

2. Increase in part-gates runners; 3. Increase 'in the power Lunder overspeed conditions, or when operating at 'constant speed under heads below normal;

4. Reduction in the dimensionsof the water afsges' and the space occu ied by the turine and itssetting; yIn-hy raulic turbines vconstructed according to revious Y ractice,

increase of specic speed as been ound to reduce art-gate eliiciencies, but to provide some a vantage in maintenance of ower ca Eacity'under conditions of varying cad. It

' as been heretofore considered impracticable to devise means forfmprovng' one of these factors without injuring the other, but I have discovered' a practicable means by which both of these factors .are improved, as

. well as the others above listed.

been verified-(experimentally, 4includes a" I have found that one Vof the chief causes of the low maximum eiiiciency of high speciiic speed turbines, or the poor art-gate eiliciencies, or the limited ower un er headsv below normal, is the ine cient discharge of `water from the runner in an. obliquedirection instead fpewdicular to the motion of the runner. which is called for by theory, and has the runner.'y If the water with such a whirli i ing motion enters a straight draft tube of ordinary design, ini'ich of the kinetic energiy contained in the whirl is lost; and in dra tubes.having a sharp bend near the runner the energy of whirl isnot only entirely lost ciencies of such 'ter discharge s oblique discharge,..

but may even increase the disturbances in lthe tube, and so tend to obstruct the flow.

.Under part-gate or overspeed conditions (such as exist under reduced head) the whirl rapidly increases `and represents a large loss o cnergly. A ..;'Ihe o ect of ,this invention is the con- 'version o the velocity'4 head comprised in `thifsl'vvliirl into a ressure head so as to increase the propo water discharged from the runner in an obliquedirection and to conduct it in a spiral passa of continually increasing cross-sec tion area, so that from the time the water leaves the .runner until it enters the tailrace its velocity is adually reduced, not only with respect t its axial com onent, as in the ordinaryV type of draft tu y, but in its total resultant value. i

, Turbine draft tubes as heretofore .usually built are Vnothing more than ordinary conical, or uniform ipes with axes either straight, or curved su stantially in one plane in any given portion and the total quantity of wadb the runner owsthrough every section. i e spiral draft tube of this invention, however, passes around the run-v .i'ier discharge space in a circumferential di- I rection,.receiving the entering water through an, annular opening on the side of the passage, and the quantity `of water flowing through each section is not the same, but. variesviith the angular ositioii of thesection. As usually 'constructe such a tube will terminato in a portion tangent to the spiral, this terminal portion forming a closed pipe simiwo lar to an ordinary draft tube.

The boundary walls of such a spiral draft tube may be formed in a lar e variety of ways; andthe invention is not 'mite'd to any particular method of design onconstruction ofspiral, These walls may be generated by a line'of any ldesired form contained in a meridian plane revolvin about a fixed axislyin in said'plane. his generating line whi e always remaining in the revolvin meridian plane is not to remain fixed relatively vso to the meridian plane, but is continually to change its length and shape as the plane revolves, in such a manner that it always'terminates in two fixed points in the plane, while continually enclosin more and more area as it advances from its initial position to its successive following instantaneous positions. The two fixed points in the meridian plane which always terminate the line will describe the upper and lower (or outer and inner) circular edges of the annular entrance space of the draft tube. The axis of revolution of the meridian plane will in eral coincide with the axis of rotation o the turbine runner. As special cases of this method of development, are included the spiral or volute ex anding radiall in a plane, and the helicoi' al or screw sur ace developing axially. The generating line may for simplicity of construction be given rectangular or circular forms, and the passage may be bounded by surfaces of revolution comlgined with helicoids or spiral cylinders, or

As ordinarily applied, the areas of the passage will increase in passin around the spiral in the same direction as t e motion of the turbine runner; but in order to obtain modified characteristics for the turbine, for special cases, the o posite direction of at: tachment can be used. The spiral draft tube of this invention is a plicable to conical turbines or turbines o the inward, outward, parallel or mixed How, action or reaction t pes, whether having horizontal 4or vertical sliafts and either one or several runners.

A further object of this invention is to `provide a draft tube of relatively small dimensions which will cooperate with a variety of t pesof turbines to improve their design an reduce the sizes of their settings. The dimensions of the turbine in the direction of the shaft axis are important/in horizontal turbines as afectin the overall length of the unit and the lengt of shaft between bearings, and in vertical units .because the depth of excavation and height of power house structure are involved. The spiral form of draft tube may be so designed as to develop but slightly in an axial direction and so permit the overall length of the turbine to be made a minimum. Furthermore, the terminal portion of the draft tube tangent to the s piral is offset from the center line of the turbine. This permits horizontal shaft units to be placed on solid foundations not pierced by the draft tube. Moreover, a deep pit can now be provided if desired beneath the generator without interferin with the tube.

In the accompanying rawings disclosing Ehe invention as applied to a hydraulic tur- Fig. 1 is a lan view of the draft tube; Fig. 2 is a iagrammatic representation of the development of the tube;

Fi 3 is a view of the discharge end of the aft tube;

Fi 4 is a sectional view on line IV--IV of Fig. 1 viewed from the right;

Fi 5 is a sectional view on line V--V of Fig. 1 looking towards the discharge end;

Fig. 1 is a plan view of a draft tube similar to that of Fig. 1 but with the spiral surface spaced' further from the runner,

Fig. 5 is a sectional view on line V- of Fig. 1. i

Fig. 6 is an elevation showin the invention applied to' another form o? turbine;

Fig;` 7 is a vertical section of fthe ferm illustrated in Fig. 6;

Fig. 8 is a. perspective view showing the manner of development of a draft tube embodying the invention;

Fig. 9 is a perspective view showing a draft tube of curved cross-section embody'- inclr the invention; Y

zFig. 10 is a similar view showing a rectan ularcross-section;

1g. 11 is a diagram showing a double spiral draft tube, one opening oppositely to t e other;

Fig. 12 shows an application of this invention to a double horlzontal turbine, and

Fig. 13 is a diagram illustrating a develo pment of the invention in which two of the sides are rectilinear.

Figs. 14, 15 and 16 are respectively a plan, sectional elevation and outside elevation showin a development in which the central core is cylindrical, the other surfaces being formed as in Fig. 13.

'In Figs. 1 to 5, the invention is illustrated in connection with a hydraulic turbine of the inward and downward How type in which A is the inlet passage from the penstock, B the runner on shaft 1, and C the draft tube. The inlet is provided with stationary guides or vanes 2 which direct the water into the guide vane passages between the adjustable guide vanes or wicket gates 3, from which the water is discharged against the blades or vanes 3 of the runner B rotating in ring 4 and discharging thewater downwardlyl andv obliquely in the direction of movement of the runner. There is thus imparted to the discharge water unfderusual conditions of operation a whirl component following the direction of the rotation of the runner and having -considerable velocity energy. To impose a minimum resistance to this whirl and transform its kinetic ener y into pressure head which can be utilized the turbine, the draft tube C is of a spir or volute form developing in -thedi-rection ofthe natural whirling path of the discharged water and gradually mcreasing in cross-section to reduce the velocity of the outflow. As herein shown, as for example in Figures 2-13, the spiral develops axially simultaneously with its radial develdesi of the sectional form of the tube in opment, although special cases the development may be principally in a4 radial plane as above described.

v -InI the embodiment illustrated in Figures I to "7, the'draft tube is formed as a void in the concrete setting ofthe turbine. It can equally well be cast or built of plates,

or castings. One of the terminals of the,

of the draft tube are generated by a line of varyinaglength and contour in the revo1ving meri 'an plane terminating atene end in the central surface of revolution 15 and at the other end at a point in the outer surface of'revolution 30 of` the .annular discharge passage receiving the dischar e from the runner andl forming the diffuser c 'amber ted 23. The smallest area of the dra tube as seen in vertical section is at the top` in Figure 2, and as` the meridian plane revolves,` the point in the successive cross-sections of theA tube corresponding to 6, travels downwardly andoutwardly on the central cone of revolution 15. This central surface may Valso be a cylinder. 'Ihe diffuser =or transition chamber 23, located between the blades and the entrance of the spiral draft tube and contained between the inner surface of revoluticn 15 'and the outer surface of revolution 30 is of generally conica'l'form.

To illustrate graphically the develo ment i 1 successive cross-sectional contours of gthe draft tube are shown lin Fig..2 s u erposed one upon the other in the same p ane, the sectional contours all havingin common the line 5, 6, across the annular inlet.

The draft tube is formed'by revolving the meridian plane so as to `bring these contours 1n order into successive angular positions, this joperation being illustrated diagram? matica ly in Fig. 8,.- In Figures. 2, 4, and 5, the sectional form of the draft Vtube is shown at 90 intervals, Figure 4`sh0winggthe contours at 90 and 270, and Figure 5 showing` the contours at 0, 180 and 360.` As shown in F'gures 3 and 5, when the draft tube has been' developed to 360 and opposite the starting point,l it has progressed suiiciently axially and radially ,to pass clear of the starting point and has a section bounded by surfaces of revolution 30 4and 15 andi spiral surface 18.

, Up to 360 the draft tubehas an annular opening at its top to receive'the discharge water, and is thereafter closed-over, as seen iny Figures 3, and 5. The' closedover portion of the tube beyond the spiral continues to expand in cross-section to the outlet 24 so that there is a continued transformation of velocity head into pressure head down to` the tall water. The amount of radial or axial meet t e-requirements of each installation and the pitch in either direction may be made'zero. Supporting piers or vanes may be provided extending across the closed-over discharge passage, sha d to conform to the proper path ofthe uid, and capable of strengthenin the passage, or directin the ilow of the -fluid therethrough, or both. uch piers or vanes are shown in Figures 14 an 15.` 1

litch of the spiral may be varied to In the draftitube shown in F igs. 1 and 5n the beginning of the s iral -at 5., 6 is.

spaced further from e runner than in Pigs. 1 to 5. Commencing with a section 4,30', 5, 6", 15', 0, successive an ular positions yof the rotating meridian p ane will give at 180 the section shown at 4, 30', 18', l5', 0, and at 90 aform of section intermediate between the two sections above outlined. At 360 the draft tube is closed over as indicated at 5, 18, 6" and passes under the entrance edge 5, 6" of the spiral. At

270 the section cut by a meridian plane .is

intermediate in shape between section at 180 and the section 4 30', 5, 18 6, 15', 0'at 360. The annular passage 23 discharge from' the turbine runner at 4 ex .tends down between the flaring surfaces ofA revolution 15 and30 to the spiral surfaces which collect and turn the flow into the tangential outletconduit leading to tail water atei.

By this invention the .discharged water is received and guided in the direction at which it leaves the runner and 4'all com nente of itsvelocity are gradually reduced and transformed into teractthe tail-water 'pressure and increase fessure head which will counv receiving the l the proportion of the total head utilized by the runner. Thus instead of opposing any component of the velocity of the discharge water and creatlng disturbances which in-V terfere with the runner the discharging currents., are allowed toow in their natural ener l of the discharge is changpd into Vpressure cad which is utilized by't e turbine.

directions and a large portion of the kinetic- Figures 6 and 7 .show the application ofthe invention to each stage of a multistage inward ilow turbine. In these figures, 31v 1s the inlet, 32 are guide blades, and 33 the first stage runner mounted'on vertical .shaft 34. To receive thewater discharged from runner 33, casing 35 is formed in accordance with this invention of spiral or volute form developing radially and axially and increasing in cross-section 'in the direction of the flow. This outlet or interstage draft tube 35 is developed morethan 360 and sufficiently radially and axiall to clear itself. At 360 it is closed-over an the radial pitch of the spiral is reduced so that it continues in a nearly circular path to the point'36 where its radial pitch is reversed and its cross-section gradually reduced to form an inlet passage 37 to another stage. The draft tube 38 of this latter stage is similar to draft tube C described above. In this double stage turbine the shaft 34 is common to bth runner 33 and runner 40.

In this 1,ray the two stages of the turbine ,are combined and the discharge water from the first stage is carried down and admitted to the second stage without any sudden changes in velocity or direction. The whirl component imparted to the water by the first runner is not iost, but its velocity head is utilized.

It is a parent that the relative amount of axial anc radial development may be varied within Wide limits and, as in case of an outward flow turbine with horizontal axis, there may be nc axial development, the draft tube then taking on the form of a spiral or volute in a single plane perpendicular to the axis of the runner.

Figure 8 shows diagrammatically, in oblique projection the development of the draft tube of this invention, the vertical line a, b, being the axis of rotation and the Planes "o bs 0a di a: b e, ff' as b1 ga hf a ba i ka cach having the section-of the tube therein indicated. The plane a, 5,41, k, is the starting plane or its position at'zero degrees. In Figure 9 is shown an exterior perspective view of a draft tube' according to this invention broken away so as to show the curved interior surface. In Figure 10 the surfaces are rectilinear, the inner surface of the tube being a surface of revolution as in the previous form. In Figure 11 is shown theA invention applied to a double draft tube in which, owlng to the simultaneous axial and radial development, one tube can lie withinthe other, both having a common -axis. In Fi ure 12, the-invention is shown applied to a horizontal double turbine unit in which the runners are within the casings 40, 41, and mounted onshaft 42, and discharge toward each other into the spiral draft tubes 44, 46

.and 45, 47, respectively. These draft tubes are right and left handed and start at different points in thc circumferences. approximately 180 apat, so that thc large section of one will be opposite thesmall section of the other, and olie can nest Within the other without consuming excessive horizontal length. By this construction, the space required is reduced, permitting the axial length of the turbine to be made a minimum. In Fi re 13, and more particularly in Fig. 16 t e draft tube is shown in successive show respectively the p an, sectional elevation and outside viewof a tube similar to that last described with the exception that the center core is modified to take the form of a cylinder.

By a plying this invention to a twin center disc argeturbine, the spiral draft tubes can begin at different points in the circumference and thus bring the large part of one opposite the small part of the other in order to save space. This saving of space is illustrated in 'Figure 12. Also with multiple sairals, they can start at different parts of t e circumference and thereby subdivide the space circumferentially, or can be radially one within another, and developing in the same or the opposite direction as shown in Figure 11. Looking down on the discharge outlet along the turbine axis, the complete discharge passae'e has a horizontal circular section at 5, 5, ut the circular partition 6, 6' divides this into an inner circu ar portion and an outer annular portion. The outer annular portion is bounded below by Athe descending helical wall whose upper edge is Vat 5, 6. The inner circular portion within the points 6, 6 has a co-axial cone with its vertex near 6, 6', and around this are the two lower descending spiral walls whose uppfel; edges are respectively 5" 6 and 5 B of t ie Ywhirl hitherto lostris utilized as pressure head to extend the range of good performance of turbines with respect to vary- .ing head, speed and gate opening. With this invention an actual increase in specific speed is allowable and may be made Without loss of eliiciency and with an actual gain in part-gate eiiicienciesv and an 'increase in the above invention the kinetic energy` the power developed under overspced condii tions and when operating at constant speeds under heads below normal. The spiral character of the draft tube of this invention enables it to carry the water away from the runner axis, reducing the dimensions of the draft tube along'the axis of the shaft. This permits the installation of a bearing close to' the runner on the discharge side, with ample space for access'to the bearing, and avolding the obstruction and losses caused by the turbine shaft passing through the draft elbow. The oi'set terminal portion of the draft tube canbe located in any convenientmanner with respect to the runner and the stream line cross section of the permits the turbine setting to be `varied within wide limits, as above pointed out.

I do not wish to confine this invention to the particular embodiments' herein described,

but intend to include v'such modifications thereof as fall within the scope of the ap-` pended claims.

Having thus described my invention, I declare that what I claim as new and desire to secure by Letters Patent, is:-

1. In a hydraulic turbine, the combination of a runner and a discharge casing in position to receive water therefrom, said casin comprising a spiral draft conduit in whic there is a greater increase in the stream line across sections at successive ositions in the direction of flow than in t e stream line cross sections of the portions of the opening for the admission of water thereinto between the beginninv of the spiral and the respective first mentioned cross sections.

2. In a hydraulic turbine, the combination of a runner and a discharge casing in position to receive water therefrom, said casin comprising a spiral Vdraft conduit in whiclgi the difference between any two successive stream line cross sectionsis greater than the stream line across section of the ortion of the opening for theadmission o water thereinto between such first mentioned two cross sections.

v 3. In a hydraulic turbine, the combination of a runner anda discharge casing in position to receive water therefrom, said casin comprising a spiral draft conduit in whic each stream line cross section is greater than ortioii of the opening for the admission o water thereinto between the beginning of the spiral and such first mentioned cross section.

' 4. In combination, a turbine runner, a spiral discharge casin around the runner axis to receive the dise arge water from the runner, and a tangent conduit to receive the Adischarp'qe water from said spiral casing, a

cross-section across the lines of iiowin said casing increasing from point to pointalong the direction of 'iowso as evervwhere gradually to reduce the velocity of the iow ltherethrough.

5. In combination, a. turbine runner and a discharge casing therefor comprising a spiral conduit and a'transition space to conduct the water from the runner to said-spiral conduit, said casin `having an outer wall spreading outward yV from the runner axis on lines of gradual curvature continuously a meridian plane varies,` graduallyfrom oint a substantial part of and outer walls and 4 from the turbine axis in the directiono the outflow so that successive meridian Sections of Said casin will have a gradual variation of area.

6. n combination, a fluid motor having a runner and a draft tube having a assage disposed circumferentially around t e discharge space of the runner and so formed that the areas of meridian,sectionsatv successive angular positions progressively enlarge at a continuall increasing rate as the' assag'e is traverse lrection.

7 In combination, a turbine'runner, a casing thereforand a velocity reducingspiral conduit around the runner axis for the dief spiral-helical disc arge conduit from .the

runner,` an outer boundary wall of said conduit having the form of a surface of revolution diver 'ng from the runner and co-axial therewitliil.

9. A fluidmotor having a runner and a spiral-helical dischar conduit therefrom, e wall of said conduit nearest the runner being formed as a sur-y 'face of revolution.

l a runner and a discharge passage-therefor bounded in part adjacent to the runner by a surface of revolution of substantial extent with elements oblique to the axis' and also bounded in art by a spiral cylinder comlposed of stralght line elements parallel to t e runner axis.

` y11. In combination, a turbine runner `and 10. A fluid motor having in a circumferential a discharge passage therefor bounded byv two surfaces of revolution co-axial with the runner withv elements oblique tothe runner axis and by a spiral cylinder-comprising elements parallel tothe runner axis.

12. In combination, a turbine runner, a discharge asse therefor bounded by two surfaces o revo ution co-axial with the runner with elements oblique to the runner axis and b a spiral cylinder -cmprising elements parallel to the runner axis, and a transition ccnduit to'conduct the water from the runner to the said discharge passage.

13. In combination, a turbine runner and a spiral discharge conduit for the water from the runner, each meridian section of sai-d discharge conduit comprising a line` at a Aiight angle to the 'runner axis and an outer boundary line parallel to said axis, 'Said lines receding respectively from and along said axis for successive meridian sections.

14. In combination, a turbine runner and a spiral discharge conduit for the water from the runner, the wall for said conduit comprising a surface of revolution of substancharge conduit comprising an inner surface tial extent adjacent to the runner with elements oblique to the runner axis, each me-` ridian section of said discharge conduit containing at least one straight line element joined to said surface of revolution.

15. In combination, a turbine runner and a discharge conduit for the water from said runner bounded in art by a helicoidal sur-r face and a spiral cyliindrical surface.

16. In combination, a turbine runner and a discharge conduit for the water from said runner, said discharge conduit havino' four, boundary walls, namely, an inner suriace of revolution, an outer surface of revolution, a helicoid surface joining said inner surface, and a spiral cylindrical surface joining said helicoid surface and said outer boundary surface.

17. In combination, a turbine runner and a. dischar e conduit for the water from said runner, t e boundary surfaces of said disof revolution, an outer surface of revolution and a spiral helicoid generated by a straight line which continually remains in a meridian plane containin the axis of the turbine, but varies in lengt and in its position in the plane' as the plane revolves aboutthe said am.

18 In combination, a turbine runner, a spiral dischargecasing therefor extending t roughout its course around the axis anincreasing distance in the axial direction from the runner, the axial distance from thc runner being suiiicient at the end of approximately a complete revolution of the .spiral to permit it to discharge into a laterally enl closed passage extending ytangentially from the spiral, and passingr beyond the first portion of the spiral in the axial direction.- Y

19. In combination, a turbine runner and a drafty tube therefor having its course in' form com' unded of a spiral and a hel-ix and boun ed by surfaces of revolution and surfaces having straight line' elements.

.20. In combination, a turbine runner and a spiral draft tube therefor, havingf a central core of which meridian sections contain curved lines concave towardthe axis.

21. In combination,'a turbine runner and a spiral draft tube therefor, bounded on he side away from the 4runner by ai curved conical surface which as it recedes from the runner yflares into an approximately plane surface normal to the runner'axis.

22. In combination, a turbine runnerwith vertical axis, a spiral discharge casing around the runner axis to receive the dis-- charge water from the runner, and vane shaped piers in the discharge casing placed edgewise to the flow lines and supporting the upper wall thereof. Y

23. The combination with a fluid motor having a plurality of stages, of an intermediate spiral discharge passage receiving the water discharged from one stage and guiding it to the inlet of the succeeding stage.

24. A multiple stage fluid motor-including a plurality of runners, and a discharge passa e for each runner, at least one of said ischarge passages being in the form ofa s iral.

25.1In a multiple'stage fluid motor, the combination with a plurality of stages, of a spiral passa `e for delivering fluid from one stage to t e next stage, and a spiral draft tube from the final stage.

26. In combination, a turbine runner, and a spiral discharge casing around the runner axis to receive the discharge water from the runner, a cross section across the lines of How in said casing increasino from point to point along the direction of ow so as everywhere gradually to reduce the velocity of the flow therethrough.

27. In combination, a turbine runner, a casin therefor, and a velocity reducing spira `conduit around the runner axis for the discharge water from said runner.

28. The method of increasing the eil'ectiveness of a hydraulic turbine which consists in permitting stream elements of the water leaving the runner to continue in their natural discharge directions along a plurality of similar spiral paths in a stream symmetrical about the turbine axis and continuous around its circumference, then guiding said stream elements in a unitary spiral stream extending through a limited portion of the circumference, and everywhere continuously expanding such spiral stream elements' in cross-section, whereby all components of velocity of the discharge water are utilized to continuously convert their velocity head into pressure head to-increase the net effective head on the turbine.

29. The method of increasing the eflective` ness of a hvdraulic turbine which consists in discharging the water from the runner vanes in its natural whirling direction and thence guiding it in a nath comprising a uni tary spiraljcourse followed bv va tangential course, and at 'all' stages of said path ,gradually spreading the stream elements to increase the cross section of-said spiral stream and correspondingly decreasing their velocity, whereby the energv Aof the wh irl component of the velocity of the water is utilized neo-gael ing the velocity of said spiral stream, whereby the energy of-the whirl component of the velocity of the water is utilized to' counteract the tail water pressure and to increase the 4net eiiective operating head. l

31. The method of increasing the effectiveness of a hydraulic turbine whlch consists in discharging water from the runner vanes in its natural direction in a plurality of spiral paths within a s lace contained between 4two surfaces of revo ution, and then guiding it in a unitary spiral stream of continuously increasing cross-section and correspondingly:

decreasing velocity whereby its kinetic encr,

gy is converted to increase the net effective pressure head o n the turbine.

32. A discharge casing for a turbinerun ner comprising inner and outer walls flaring outwardly from the turbine axis and a side wall connecting said inner and outer walls' and receding from said axis in the direction .0f flow of the discharge so as to form a pas sage guiding and decelerating the discharge l along spiral lines and continuously converting its velocity energy -into pressure 4head to reduce the back pressure on the turbine '33. In a hydraulic turbine, the combina# tion with a runner, ofla discharge casing in which the differences in area between suc'- cessive cross sections spaced at equal 4angular intervals about the runner axis continuously increase in the direction of flow.

34. In combination, a turbine runner and a discharge casing therefor comprising a spiral conduit and a transition space to conduct the water from the runner to said spiral conduit, said casing having its elements everywhere smoothly curved and free from abrupt changes of direction whereby it guides both the whirling'components `and the 0 bmerotor, means for outwardly dlrectmg changes and meridian sectionsthereof being free from points of inflection except at-their outermost parts.

35. 4In combination, a turbine runner anda discharge passage therefor bounded in'part by a surface of revolution having a generating line so curved that successive elements pf this line continuously increase their angle of inclination with respect to the runner axis as they recede from the'runner so as to' approach more and more nearly to perpendicularity to the axis, and adjoining said surface of revolution a spiral cylinder vomposed of straight line elements parallel to the runner axis.

36. In combination, a turbine runner an a spiral draft. tube therefor, bounded in part' by two surfaces ofrevolution co-axial with the runner, each generated by lines convex toward a point on the runner axisdistant frfom the runner on the discharge side thereo 37. In combination, a turbine runner and a discharge passage therefor', bounded by two sur-faces of revolutionco-axial with the runner, each generated by a lineconvex toward a point on the runner axis distant frm the runner on the discharge side thereof, and bya spiral cylinder comprising elements parallel to the runner aris.

38. 'In combination, a' turbine' runner and a spiral dra-ft tube therefor bounded in part by a surface-of revolution eo-axial with the runner, generated by a line convex 4toward a point on the runner axis distant 'from the runner on" the discharge side thcreofrv 39.. In. combination, an axial discharge turbine rotor, and a lspiral draft tube formed to decelerate the ilow of the fluidl discharged from said rotor. l v

40. In combination, ian axial discharge turbine rotor and means for simultaneously guiding the fluid discharged from said rotor in a common spiral course and decel- "eratin* the flow of said fluid. positionto receive Water therefrom, sald casmg 4comprising, a spiral draft conduit in..

said directionnging means for further -decelerating said ow.

43. I'n combination, an axial discharge turthe axial dischar e flow and for partially dcceleratin said gow, and means forming a s iral co ectin chamber surrounding said ecelerating directionchanging means for further" decelerating said iow.

44. I n combination, an axial discharge tur.. bine rotor, guide vanesextendi-ng longitudi- 4 nally of the turbine axis for controlling the inlet to said turbine. means for outwardly directing the axialvtdischar iow and for partially decelerating said ow, and means forming a spiral collecting chamber communicating with said direction-changing means for further decelerating said flow.

45. In combination, a turbine having an inwardly directed inlet and an axially directed discharge, means for axially directing the inward inlet flow, means for outwardly directing 'the axial discharge flow and for initially decelerating said flow, and

means forming a spiral collecting chamber 130 'turbine and a single body within and sursaid direction.

rounded by said tube, the said body having a curved sectional profile andan unobstructive outer surface, the diameter of said body gradually increasing in the outlet direction, and the inner part ofthe tube surrounding said body being gradually enlarged in the 48. In combination, a draft tube for a turbine, a turbine runner, and 'a-single body. within and surrounded by said' tube and leadinfr directly from the runner, the said- .body raving a curved sectional profile and an unobstructing outer surface, the diameter 'of said body gradually increasing in the outlet direction, and the inner part of the tube surroundin said body being gradually enlarged in t e said direction.

49. In combination, a draft tube for a turbine; a rotatable turbine runner; and a single non-rotatable body within and surrounded by the tube, the surface of the runner leading directly into that of the body, said last-named surface being unobstructing and said body having a curved sectional profile and of a diameter which gradually increases in the outlet direction, and the inner'part of the tubesulrounding said body tion. e

50. A draft tube for` a turbine and a single body projecting into'the tube from a wall thereof and surrounded by part of the tube, the said body having an outer surface, the diameter of which gradually increases in the outlet direction, and the inner part of the part of the tube surrounding said body being gradually enlarged in the said direction.

51. A draft tube for aturbine and a single body within the tube and connected with aA wall thereof and surrounded by part of the tube, the said body having an outer surface, the diameter of which gradually increases in the outlet direction, and the inner part of the art or the tube surrounding saidbody be ng gradually enlarged in the said direction. i.

52. The combination with Va duid motor having a runner with an axial discharge, of

a draft tube therefor comprisingr inner and outer flared surfaces of revolution gradually cnrylng away fromtbe axlaldirection adjacent the runner to form between them a' being gradually enlarged in the same direcflaring annular passage extending from the runner and adapted to receive a whirling discharge and guide it and decelerate it on expanding spiral lines so as to decelerate both the rotational and meridian components of velocity and convert them into effective pressure head.

53. The combination with a fluid motor having a runner with an axial discharge, of

a draft tube therefor comprising an outer surface of revolution convex toward the runner axis and curved to gradually turn' the outer flow lines outward from an' axial direction adjacent the runner toward a radial direction, and an inner core having a surface of revolution 'spaced from sald outer surface ,so Vas to provlde an annular passage extending from the runner and adapted to guide a whirling dischar e on expanding spiral lines to continuous y and gradually reduce the velocity of flow and convert velocity head into pressure head while the liow is being turned outward.

54. The combination with a fluid motor having an axial discharge, of a draft tube atherefor comprising a central core extending into proximity with said motor and having an inner conical surface of revolution concave towardthe axis of the runner to gradually turn the innerflow lines outward towardia radial direction. and an outer portion having a surface .of revolution spaced from the inner surface of revolution so as to provide an annular passage adapted toA guide a whirling discharge on expanding spiral lines to continuously and gradually reduce the velocity of flow and convert velocity head into pressure head while the ow is being turned outward. n

55. An annular discharge passage for a fluid motor having ,uniform entrance width -and comprising an outer portion with a surface of revolution convex toward the runner axis and flaring outward from adjacent im i the runner, and an inner core having a conical surface of revolution with its apex at the runner axis and adapted to gradually turn the inner How lines outward toward a radial direction, said inner and outer surfaces being formed and spaced with relation to each other so that the annular passage is adapted to guide a whirling discharge on expanding spiral lines to continuously and gradually reduce the velocity of flow and convert velocity head int-o pressure head whilethe flow is being turned outward.

56. An annular discharge passage for a Huid motor having uniform entrance width' and comprising an outer portion with a surface of revolution convex toward the'runncr axis, vand an inner core having a conical surface of revolution beginning close to the discharge end of the runner and adapted to gradually turn thc inner flow lines outward toward a radial direction, said inner and outer surfaces being formed and s aced with relation to each other so that t e annular passage is adapted to guide a whirling discharge on expanding spiral lines to continuously and gradually reduce the velocity of flow and convertl velocity head into pressure the ilow is being turned outrunner and curving to gradually turn the inner flow lines outward toward a radial direction, said inner and outer surfaces being spaced with relation to each other so as to provide an annular passage adapted to guide a whirling discharge on expanding spira lines to continuously and gradually reduce the velocity of flow and convert velocity head into ressure head while the flow is ybeing turne outward.

58. The combination with a turbine runner of inlet means therefor havingv guiding means adapted to impart a variable whirl to the inflow, and a draft tube passage for the discharge from said" runner comprising an outer surface of revolution convex toward the runner axis and curved togradually turn the outer flow lines outward toward a radial direction, and an inner surface of revolution spaced from said outer surface so as to provide an annular passage adapted to guide a whirling dischar e on expanding spiral lines to continuou y and gradually reduce the velocity of flow and convert velocity head into pressure head while the flow is being turned outward, said surfaces of l revolution being spaced with relation to each other to give a rate of deceleration of the flow greater than that of a straight conical tube the sides of which taper at 15 with respect to the axis.

59. The combination with a turbine runner of inlet means therefor having guiding means adapted to impart a variable whirl to the inflow, and a draft tube passage for the discharge from said runner comprising an inner conicalfsurface 'of revolution concave toward the axis of the runner to'gradually turn the inner flow lines outward toward a radial direction, and an outer surface of revolution spaced from the inner surface of revolution so as to provide an annular passage adapted to guide a whirling discharge on expanding spiral lines to continuously and gradually reduce the velocity of flow and convert ,velocity head into pressure head while the' flow is being turned outward* said surfaces of revolution being spaced with relation to each other to give a rate of deceleration of the vflow greater than thatl of a straight conical tube the sides of' which taperat 15 with respect to the axis.

60. In combination, a turbine runner-with i vertical axis, a masonry foundation structure below the runner having an outflow conduit formed therein and' a series of,

metal stay vanes in said conduit standingl ereof, each such stay vane having ture below the runner having an outflow' conduit formed therein and a series of metal stay vanes in said conduit standin around 1 said vertical axis and supporting t e upper wall of said conduit on the lower wall thereof, said stay vanes being shaped in conformity with spiral paths of flow of the water.

62. In combination,` a turbine runner with vertical axis, a masonry foundation structure below the runner having an outflow conduit formed therein and a series of metal stay venes in said conduit standin around said vertical axis and supporting t e. upper wall of said conduit on the lower w'all thereof, said vanes shaped in conformity with expanding spiral aths of ilow of the water.

63. In combination, a turbine runner with vertical axis, a masonry foundation" structure below the runner having an outflow vconduit formed therein and a series of metal stay vanes in said conduit standing around said vertical axis and supporting e upper wall of said conduit on the lower wall thereof, said stay varies being similarly inclined to radii thereto from said axis.

64. In combination, a turbine runner with vertical axis, a masonry foundation structure below 4the runner-having an outflow conduit formed therein and a series of metal stay varies in said conduit standing around 'mthe 65. In combination, a turbine runner with A vertical axis, av masonry foundation structure below the runner havingV an outflow conduit formed therein, said conduit spreading downwardly and outwardly around said axis on every side, and a series ofmetal stay varies in said conduit stand- 'ing around vsaid vertical axis and supporting the upper wall of said conduit on the lower Wal thereof, each such stay vane having small thickness transverse to the direction of flow and bein setat a suitable angle to a plane throug the vane containing the turbine axis, so as tooil'er small resistance to the outtlowing water. l t 66. In combination, a turbine runner wlth vertical axis, a masonry foundation Structure below the runner having a spiral outtiow conduit formed therein and a series of metal stay vanes in said conduit standmg around said vertical axis and supporting the upper wall of said conduit on the lower wall thereof, each such Vstay vane sha ed in conformity with spiral paths of ow of the water.

67. In combination, a turbine runner with vertical axis,'a masonry foundation'structure below the runner having a spiral out- `iow conduit formed therein and bounded on its lower and inner side by an upward conical projection of the lower wall of said conduit coaxial with the runner, and a series of metal stay vanes in said conduit standing around said vertical axis and supporting the upper wall of said conduit on the lower wall thereof.

68. In combination, a turbine runner with vertical axis, a masonry foundation structure below the runner having an outflow conduit formed therein, the lower wall of said conduit projecting upward conically toward the runner and coaxial therewith, and a series of metal stay vanes in said conduit standing around said vertical axis and supporting the upper wall of said conduit on the` lower wall thereof.

-69. In a hydraulic turbine the combination with a runner discharging the flow axially and with a forward tangential component at all gate openings so that the absolute velocity of the discharging water always has a component in the direction of rotation of the runner, of a spiral draft tube receiving the discharge from said runner and decelerating it to convert its velocity energy into effective pressure head. 70. In a hydraulic turbine the combination with a runner discharging. the flow axially and with `a forward tangential component` at all gate openings so that the absolute velocity of the discharging water always has a component in the direction of rotation of the runner, of a spiral draft tube receiving the discharge from said runner and decelerating it to convert its velocity energy into effective lpressure head,'the initial point of the spira being situated on that side of the 1t'ubine toward the final outlet of the draft 71. In a hydraulic turbine the combina- 'tion with a runner discharging the flow ax' solute velocity of the discharging water al ways has a component inthe direction of rotation of the runner, of a central conical core spreading the discharge water outward in all directions andv a spiral draft tube receiving the discharge from said runner and decelcrating it to convert its velocity energy ilitdei'ective pressure head. 72I In 'a hydraulic turbine the combination with a vertical shaft turbine runner discharging 'the flow in a` enerally axial direction, of a shaft con uit comprising a downwardly directed initial passage receiving the How from the runner and decelerating it to convert velocity head into ressure head, and a substantially horizonte terminal passage receiving the flow from said initial passage and laterally offset with respect to the center line `of said turbine.

73. In a hydraulic turbine the combination with a vertical shaft turbine runner discharging the flow in a nerall axial direction, of a draft conduit ormed in a concrete substructure and 4comprising a downwardly directed initial passage receiving the flow from the runner and continuously decelerating it to convert velocity head into pressure head, and a substantially horizontal terminal pas sage receiving the flow from said initial passage and laterally o'set with res )ect to the center line of said turbine, sai terminal passage continuing the deceleration ofthe flow to further. convertthe velocity head into effective pressure head.'

74. In a hydraulic turbine the combina- A tion with a turbine runner adapted to discharge the flow as a whirling axially progressing stream, of a draft tube receiving said flow andi formed with cooperating surfaces extending in a generally axial direction near the runner and turning toward an outward direction away fromV the axis and spaced to gradually and continuously decel-` erate the whirling velocity components of said flow, ,while simultaneouslyturning the meridian components of said low from axial toward a direction outwardly from the axis.

75. A draft tube for a hydraulic turbine adapted tofreceive from the runner of said turbine a whirling axially progressing ilow and gradually and continuously toxdecelerate both the meridian and whirling velocity components of said flow while`turning said flow from axial to a. direction outward away yfrom theaxis, and an enlarging discharge passage receiving said outward flow and having a general direction substantially normal to the runner axis but horizontally otlset with respect to said runner axis so as to re-I ceive a portion of said low tangentially.

76. The combination with a hydraulic turbine of a` draft tube therefrom comprisingr a central conical core beginning closely ads jacent to the discharge edge of the runner, and side surfaces extending from said runner and 'cooperating with said core, said core and side. surfaces forming between cave and be 'inning closely adjacent to the discharge e ge of the runner, and correspondiugly convex side surfaces extending egim said runner, andy cooperatin with said v'1e-bre, said core and side surfaces orming between them an annular passage lf lgradually increasing in cross section'in the direction of flow so as to turn the-flowl from axial toward a. direction outward away from the axis and simultaneously to convert the velocity head ofthe discharge into effective pressure head at the outlet of said annular passage.

, 78. In a hydraulic turbine the combination witha vertical shaft turbine runner adapted to discharge the flow substantially axially, of a draft tube receiving said flow and formed with cooperating surfaces extending in a generally axial direction near the runner and turning outward away from the axis and spaced to gradually and continuously decelerate said flow while simultaneously turning the How from axial to an outward direction away from the axis within' a relatively short axial distance below said runner, so as to reduce the overall depth of the turbine, the vertical height of said draft tube being less than three times the diameter of said runner.

79. A draft tube for a hydraulic turbine comprising a passage with its surfaces formed to give a gradual and continuous increase in cross Sectional area ofthe How while simultaneously turning the flow from an axial direction at entrance toward an outward direction away from the axis at discharge'and with a spiral surface beginning in the axial flow portion of the tube and exerling to the outward fiow.; portion tof the 8f). A draft tube for a hydraulic turbine comprising a passage with its surfaces formed to give a gradual increase in cross sectional area of the flow while turning the How from an'axial direction at entrance towardY an outward direction away from the axis at discharge and with a surface formed as a spiral with an entrance edge extending transversely across the flow in the generally axial portion of said tube so as to divide said iiow.

81. A draft tube for a hydraulic turbine comprising a passagewith its surfaces 'formed to give a` gradual increase in cross sectional area of the flow while turning the tiow from an axial direction at entrance toward an outward direction away from the axis at discharge and with asurface formed as a spiral with an entrance edge extendino transversely across theow in the generell axial portionof said tube so as to divi e said flow and with its dischar e ortion extending in a generally outwarg dlirection away from the axis to form a surface of the discharge portion of said draft tube.

82. A draft 4tube for a hydraulic turbine comprising a passage with its surfaces formed to give a gradual increase in cross sectional area of the tlow while turning `the fiow from an axial direction at'entrance toward an outward direction away from the axis at discharge and with one of its surfaces formed as a spiral with an entrance edge extending in a radial plane transversely across the fiow inthe generally axial portion of the tube so as to divide said flow and with its discharge portion extendin in a generally outward direction away rom theaxis to form a surface of the discharge portion of said draft tube, said spiral surface gradually and continuously twisting from the radial plane of its entrance edge to the generally outward direction of its discharge portion.

83. A draft tube for a vertical shaft hydraulic turbine comprising a passage with its surfaces formed to give a gradual lncrease in cross sectional area of the flow .while turning the flow from vertical direotlon at entrance toward -a horizontal direction at discharge and with a surface formed as a spiral with an entrance edge extending transversely across theow in the generally vertcal portion of the tube so as to divide said flow and with its discharge ortion extending in a generally horizonte direction to form a surface of the discharge portion of said draft tube, 'said spiral surface gradually and continuously twisting from the direction of its entrance edge to a generally vertical position in the discharge portion of the ldraft tube.

84. In a hydraulic turbine, a discharge passage formed to receive the water vertically at entrance and to turnlt and discharge it horizontally, and a dlvldmg wall or partition therein, having an entrance edge near the inlet end of said tube ex tending approximately horizontally along a radius of the tube, and said part 1t1on having a surface generated by the rotation of a. line about the axis while said generatlng line moves downwardly so as to form a emerally helicoidal surface for said partitlon m the entrance portion thereof. l

85. In a hydraulic turbine, a discharge passage formed to receive the water vertically at entrance and to turn 1t and discharge it horizontally, and a dividing wall l let portion having aY generally helicoidal form so that, at entrance, it is inclined to a meridian plane to conform to the tangential components of the flow discharge by the runner.

86. In a hydraulic turbine a draft tube adapted to convert velocity head into pressure head and comprising Walls formed to receive the flow axially and turn it toward an outward direction away from the axis and with a partition in the draft tube extending transversely across the flow lines and dividing the `Ilovv.

87. In a hydraulic turbine a draft tube adapted to convert velocity head into pressure head and com rising walls formed to receive the flow axially and turn it toward an outward direction away from the axis and with a partition in the draft tube having its entrance edge extending transversely across'the flow lines to divide the flow and with its surfaces forming guiding surfaces for the flow and curved around to extend as surfaces of the discharge portion of the draft tube.

88. In a hydraulic turbine having a vertical shaft runner, a draft tube adapted to convert velocit head into pressure head and comprising wa s formed to receive the How vertically and turn it toward a horizontal i direction and with a partition in the draft tube having its entrance edge extending transversely across the tube to divide the vertical flow and having a surface curving around to guide the flow and to form a generally vertical surface in the discharge portion of the draft tube.

89. A draft tube which when applied to a vertical shaft turbine comprises surfaces formed to receive the water vertically at entrance and to turn it and discharge it horizontally, said surfaces including a portion curving from a side surface of the cntrance portion to turn the ow and forni a deilecting oor surface in the horizontally directed portion of the tube, and a pier meinber extending from said floor across the draft tube passage and having its inner entrance portion curved out of a plane surface to conform to a direction of flow at an an le to the final discharge direction.

n testimony whereof I aiix my signature.

LEWIS FERRY MooDY.

let portion having a generally helicoidal form so that, at entrance, it is inclined to a meridian plane to conform to the tan ential components of the flow discharge y the runner.

86. In a hydraulic turbine a draft tube adapted to convert velocity head into pressure head and comprising walls formed to receive the fiow axially and turn it toward an outward direction away from the axis and with a partition in the draft tube extending transversely across the flow lines and dividing the ilow.

87. In a hydraulic turbine a draft tube adapted to convert velocity head into pressure head and com rising walls formed to receive the How axially and turn it toward an outward direction away from the axis and With a partition in the draft tube having its entrance edge extending transversely acrossthe How lines to divide the flow and with its surfaces forming guiding surfaces for the flow and curved around to extend as surfaces of the discharge portion of the draft tube.

88. In a hydraulic turbine having a vertical shaft runner, a draft tube adapted to convert velocit head into pressure head and comprising wa 1s formed to receive the flow vertlcally and turn it toward a horizontal direction and with a partition in the draft tube having its entrance edge extending transversely across the tube to divide the vertical iiow and having a surface curving around to guide the flow and to form a generally vertical surface in the discharge portion of the draft tube.

89. A draft tube which when applied to a vertical shaft turbine comprises surfaces formed to receive the water vertically at entrance and to turn it and discharge it horizontally, said surfaces including a portion curving from a side surface of the cntrance portion to turn the iow and form a deecting floor surface in the horizontally directed portion of the tube, and a pier member extending from said floor across the drafttube passage and having its inner entrance portlon curved out of a plane surfface to conform to a direction of iow at an an le to the final discharge direction.

n testimony whereof I ax my signature.

LEWIS FERRY MOODY.

Certicate of Correction.

It is hereby certiiied that in Letters Patent No.'1,604,361, granted October 26, 1926, upon the application of Lewis Ferry Moody, of Troy, New York, for an 1mprovement in error appears line 7 5, claim 72, for the word Dr'aft Tubes for Hydraulic Turbines or Other Fluid Motors, an in the printed specication requiring correction as follows: Page 10, shaft read draft; and that the sald Letters Patent should be read with this correction therein that the same may conform to the record lof the case in the Patent Oliice.

Signed and sealed this 30th day of November, A. D. 1926.

[SEAL] M. J. MOORE, Acting ommtz'ssiofwr of Patents. 

